Double sickle reciprocating cutting assembly driven by a free piston internal combustion engine



March 6, 1962 w. TENNEY DOUBLE SICKLE RECIPROCATING CUTTING ASSEMBLY DRIVEN BY A FREE PISTON INTERNAL COMBUSTION ENGINE Filed Jan. 14, 1960 zm zzvron.

WILLIAM L.TENNEY MQW ATTORNEYS 3,023,563 DOUBLE SICKLE RECWRGiIATiNG QUTTING ASSEMBLY DN BY A FREE PliSTON IV- TERNAL CGMBUSTIQN ENGHNE William L. Tenney, Crystal Bay, Minn. Filed Jan. 14, 196i), Ser. No. 2,411

7 Claims. (Ci. 56-265) This invention relates to internal combustion engines and to cutting machines, particulary to such cutting machines as reciprocating saws, clipper-bar mowing machines, and the like, which are power driven by a selfcontained internal combustion engine.

Presently used small internal combustion engines, for example of the single cylinder type used to drive portable tools, mowing machines, etc., are of the conventional construction wherein a stationary cylinder is mounted on a frame and a piston reciprocates within the cylinder and drives a rotary crank shaft through a connecting rod. The crank shaft in turn is mounted in bearings within a crank case on which the cylinder is fixed, and the engine has a rotary output at the crank shaft. The piston is driven by reason of expansion of a combustible charge which is burned within the power cylinder defined by the piston and cylinder, and as a result of such expansion the piston moves axially within the cylinder. In such conventional constructions the cylinder and crank case are mounted stationary, or perhaps on compliant mounting bushings which absorb some vibration, but the output from the engine is solely through the rotating crank shaft, requiring conversion of the linear motion of the piston and connecting rod into rotary motion ofthe crank shaft with attendant power loss. Also, if these engines are used to drive parts, such as' cutters or reciprocating saw blades which need a linear motion drive, then a further rotary to linear motion converting mechanism is needed, and as a consequence further power loss is encountered.

The present invention provides a novel internal combustion engine in which both the cylinder and the piston are mounted for movement, within limits, on a frame, and wherein each of them is connected to an output. Thus, the cylinder moves as well as the piston as a result of combustion of a charge therein, and linear movement of the cylinder is transmitted to an output as well as the linear movement of the piston.

The well known type of internal combustion engines, used for driving various cutting machines such as portable saws or lawn mowers and similar mowing machines, employs a rotating crank shaft which is driven by a piston moving axially within a stationary cylinder. Many such engines are presently in use, operating on both the four cycle and two cycle principles. Because of the rotary output of these engines it is often the custom to adapt the cutting members of the machine which they are driving to such rotary motion, and hence there are a number of lawn mowing machines having rotary cutting elements either in the form of rotating sharp blades or rotating reels cooperating with a stationary blade on the mower frame. In the case of portable saws or the like, it is often the custom to provide a continuously moving chain member carrying cutting teeth which always move in one direction from a rotary drive, i.e., the well known types of chain saws.

Various systems have been proposed to use reciprocating cutters powered by such rotary engines, but these require complicated motion converting mechanisms or linkages which are a source of difiiculty both from the manufacturing and maintenance standpoint. It is well recognized, however, that the reciprocating types of cutters are much safer to use, and in many cases do a better Patented Mar. 6, 1962 job of cutting than, for example, the rotating blade type of mowing machine.

Accordingly, the primary object of this invention is to provide a novel internal combustion engine in which both the cylinder and the piston are mounted for relative movement in response to combustion of a charge therein, and wherein direct output connections are provided to both the cylinder and the piston.

Another important object of this invention is to provide a novel cutting machine construction wherein a pair of cutting blades are supported for cooperative cutting action by reciprocating movement of the blades relative to each other, and wherein the drive to each of these blades is obtained directly from an internal combustion engine which has a reciprocating linear-motion output, as distinguished from a rotary output.

Another object of the invention is to provide such a cutting machine wherein the piston and cylinder of the engine each has a separate direct drive connection to one of the blades, and wherein the entire engine unit is mounted for free reciprocating movement on a frame, with resultant reduction in vibration transmitted to the frame and hence to the operator of the cutting machine.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawing and the appended claims.

In the drawing- FIG. 1 is a schematic perspective view, partially in section, illustrating the basic arrangement and features of an engine and a cutting machine in accordance with the invention;

FIG. 2 is a longitudinal sectional view through an internal combustion engine of a type such as represented in FIG. 1;

FIG. 3 is a sectional view taken on line 3-3 of FIG. 2;

FIG. 4 is a somewhat schematic side view, with some parts broken and shown in section, illustrating a suitable frame and mounting for the cutting machine;

FIG. 5 is a sectional view taken on line 5-5 of FIG. 4;

FIG. 6 is a section w'ew taken on line 66 of FIG. 4;

FIG. 7 is an enlarged detail view, partly in section, of a portion of FIG. 5; and

FIG. 8 is a detail view from one side of FIG. 7, with parts broken out and in section.

Referring to the drawing, which illustrates one embodiment of the present invention, FIG. 1 shows schematically the general arrangement of parts in an engine and a cutting machine as provided by this invention. The cutting action is provided by a pair of cooperating toothed cutting blades 10 and 12, respectively, which are mounted on bars 14 and 15. These bars are supported in any suitable manner for relative longitudinal movement, so as to produce relative movement of the cutting teeth which results in a cutting action as well known.

The novel internal combustion engine which drives these cutters is provided by a cylinder member 20 and a piston member 22 mounted within the cylinder member and having a piston rod 25 which extends therefrom through one end of the cylinder member. The piston and cylinder members cooperate to define a variable volume power cylinder 28 in which combustible charges are burned, and a biasing means in the form of a spring system 39 operates between the piston and cylinder members in a direction normally to compress a charge therein, and to be acted upon by forces resulting from combustion of a charge and expansion of the products of combustion in the power cylinder.

The cylinder member 20 is connected directly to bar 15 as shown schematically at 32. Piston rod 25 is fastened to the end of a cup shaped output member 35 which is received coaxially about the end of cylinder member 20, and which in turn has a direct drive connection 37 to the bar 14. Suitable openings 38 in the end wall of cup 35 are provided to permit escape of air entrapped between the cup member 35 and the end of cylinder member 20 which it surrounds.

In operation, as a charge is supplied to the power cylinder 28 it is compressed due to relative movement there between which results from the biasing force of the spring system 30. The compressed charge is then ignited in any suitable manner and combustion of the charge produces relative movement of the piston and cylinder members (in opposite direction) against the biasing force of the spring system, and against whatever load may be imposed upon the cutters and 12 which move with the piston and cylinder members, respectively, due to their above described direct connection to these members.

The spring system is of such strength that it will absorb and return substantially all energy imparted thereto, without bottoming, during normal operation of the engine. Thus, at the end of the power stroke of the piston and cylinder members the products of combustion will be exhausted from the power cylinder and substantially all of the energy stored in the spring system will be returned through the piston and cylinder members to produce an effective cutting stroke of the cutters 10 and 12 in the opposite direction from the stroke which resulted from combustion of a charge in the engine.

The spring system thus provides an effective output stroke in the other direction from combustion of a charge, and at the same time a portion of the energy returned from the spring system will serve to compress an additional combustible charge supplied to the power cylinder 28. Therefore, the output is a direct reciprocating drive to the cutters 10 and 12 which causes them to reciprocate oppositely to each other and produces an elfective cutting action between the teeth thereof.

Certain details of an engine suitable for this purpose, and as constructed in accordance with the invention, are shown in FIGS. 2 and 3, wherein the cylinder member includes a cylinder block provided with cooling fins 42 and a liner 43. One end of this block is closed by a cylinder head 45 which also is provided with suitable cooling fins 46, and which is secured to the cylinder block 40. The head may carry a suitable igniter, for example in the form of a spark plug 47, the electrodes of which are shown in FIG. 2.

The cylinder block is mounted on the main body having cooling fins 51 (FIG. 3), and which includes a central bore 52 aligned with sleeve43, and an enlarged bore 55 which extends through to the other end of the body, and across which is mounted a head 57 having a central aperture 58 for passage of the piston rod 25. The piston 22 is provided with a reduced neck portion 60 connecting with an enlarged central land portion 62 which fits in substantially sealing relation with the bore 55, defining, on the one end surrounding neck 60, a cooling chamber 65 from which air circulates in and out through openings such as indicated at 66, and at the other end, within head 57, a scavenging pump chamber 67. The scavenging pump chamber in turn is connected through passages 68 with inlet ports 70 through the cylinder liner, and exhaust ports 72 are also provided for passage of exhaust gases from the power cylinder 28 when these ports are uncovered by the piston.

The spring system 30 includes an outer heavier main spring 75 acting between the outer lip 76 of, a cup 77 movable within bore 55, and a lighter inner spring 78 which acts between the bottom of cup 77 and a shoulder 79 formed on the piston member adjacent the end of rod 25. This rod is preferably hollow through a portion of its length, as shown in FIG. 2, and is provided with opening 80 through which the working fluid for the engine is supplied to the scavenging pump chamber 67. This working fluid may be either in the form of air, or a fuel-air mixture,

depending upon the manner in which fuel is supplied to the engine, i.e., through a carburetor or by direct injection of liquid fuel. The Working fluid may be supplied from any suitable device, which may be attached to the fitting 82 at the end of hollow piston rod 25, through a flexible tube to accommodate the movement of the piston rod and cup member 35 which is secured thereto.

The particular embodiment shown in FIGS. 2 and 3 normally will operate as a two-cycle engine, with combustion on each working stroke against the biasing force of the spring system, and with the spring system in turn providing the force necessary for a compression stroke on each movement of the piston and cylinder members in the opposite direction. The working fluid will be supplied through passages 68 from the scavenging pump chamber when the inlet openings 70 are uncovered. Also, in accordance with the usual practice the exhaust openings 72 may be somewhat larger than the inlets, and extend closer to the head 45 as shown, such that the exhausts will be opened first at the end of the power stroke to initiate a flow of exhaust gases from the power cylinder before inlet of a fresh charge commences.

The engine just described has fixed output connections from both the piston and cylinder members, as discussed above in connection with PEG. 1. Obviously, these outputs may be connected to a variety of different types of mechanisms, for example toothed cooperating cutter bars as previously described. The engine is mounted in such a manner that both the piston and cylinder members are free to move in a direction parallel to the axis of the cylinder member. A typical mounting arrangement is shown in FIGS. 4 and 5, wherein the engine is shown somewhat schematically.

Thus, referring to FIG. 4, the mounting framework of the engine, as it might be employed in a trimming cutter, for example, is provided by a pair of loops of rod or tubing 1% and 102 (FIG. 5) forming guideways'1ll3 at the lower end which accommodate slide bearings 105 carried in extensions 107 from the cylinder member 20, which normally has the least actual motion relative to a fixed point in space. The upper portions of the frame members 100 and 102 may be joined over the engine, and may be connected to upper frame members, portions of which are shown at 168, to connect with a suitable handle and supporting wheels or the like, as may be desired.

The free movement path of the engine on the frame must have some limits, to maintain the engine within a given portion of the guideways, and to protect against damage in the event of misfires, etc. For this purpose suitable buffer means are provided, for example in the form of discs 110 of resilient material which are fastened to the frame in any suitable manner, and which provide outer limits to movements of the engine parts on the frame.

The upper output bar 114 (which corresponds to bar 14 in FIG. 1) is connected to the bracket 137 which extends from cup member 35, and which also extends at least partially around the lower output bar 115. These bars are held in aligned relation by means of g-ibs 117 (FIGS. 4-7) which extend from both the forward and rear brackets 132 and 137 around the upper and lower bars, providing for aligned relative sliding movement between these output bars. Bar 114 includes an elongated slot 118 (FIG. 4) over which the forward bracket 132 extends, carrying the gibs 117 and incorporating a clutching device 120. Each of these bars extends forwardly of the frame, as shown in FIG. 4, and carries one of the two cooperating cutter blades 10 and 12, which thus reciprocate respectively with the output bars 114 and to produce a cooperative cutting action.

Details of the aforementioned clutching device 120 are shown in FIGS. 7 and 8. This device includes a shaft 122 having an enlarged head 124 with a beveled dog surface or end 125 which is adapted for engagement within a complementary beveled notch 127 within the interior surface of the bracket 132. The shaft 122 extends through slot 118 in upper bar 114, and is slidably received in a hole 130 through the lower bar 115, having an enlarged knurled head 133 attached to it (for example threaded and locked as shown in FIG. 7) beneath the lower bar. A spring 134 operates beneath the head 124 and the surface of bar 115, surrounding shaft 122 and biasing the dog 125 into an engaged position as shown in FIG. 7. The knurled head 133 is provided with a cam surface 135 on a side of its under face (FIG. 8), engaging a pin or protruberance 138 extending beneath bar 115 and spaced from the vertical axis of shaft 122.

With this arrangement manual rotation of the knurled head will cam it downwardly and withdraw the dog 125 from its engaging position, against the spring bias, and with this clutching arrangement disengaged the drive connection between cylinder member 20, through bracket 132, to its output bar 115, is interrupted. This permits the cylinder member to move freely on its mountings, without load, and facilitates the starting of the engine, in the same manner as described in greater detail in said copending parent application. Once the engine is running the knurled head 133 may be turned to the position shown in FIG. 8, and the dog 125 will cam into engagement with the notch 127, thereafter providing a completed drive connection to the output bar 115. It will be understood that the interior surface of bracket 132, in which the notch 127 is formed, will be of sufiicient length over the output bars to prevent the clutch head 124 from passing outside the bracket during the normal relative motion of starting.

Obviously, the arrangement shown is but one of many types of configurations to which the present invention is applicable. For example, the framework may include a suspension, a handle and supporting wheels,'and the cutting blades could be mounted in any suitable manner to provide a mowing machine or other cutting machine. Other suitable configurations will suggest themselves to those skilled in the art.

FIGS. 4 and 6 show suitable apparatus for retaining the cutters 10 and 12 in proper contact. This includes a bolt 140 having its head preferably recessed in cutter 12 and extending upwardly through a hole in that cutter and through a slot 142 in cutter 10, which slot is elongated lengthwise of the cutter. The bolt passes upwardly through a hole in a retaining plate 145. The assembly of cutters and plate 145 is urged into sliding contact by a conventional spring washer 147 surrounding the bolt and held in place by the nut 148.

The present invention thus provides a novel type of internal combustion engine wherein power output connections are coupled to both the piston and the cylinder of the engine, and wherein both the piston and the cylinder move in response to combustion of a charge in the cylinder. Direct output connections from each of these members provide reciprocating power outputs which operate in opposite directions, and are especially suited to driving a pair of cooperating and oppositely reciprocating cutter members such as toothed cutters or the like which may be designed for any number of cutting operations, such as sawing, mowing, trimming or the like.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. An internal combustion engine of the character described, comprising a cylinder member and a piston movable in said cylinder member defining therewith a power cylinder including a combustion chamber, means mounting said cylinder member and said piston for relative movement with respect to each other in a direction parallel to the axis of said cylinder member, means connected to supply a combustible charge into said power cylinder for combustion in said power cylinder to produce opposite movements of said cylinder member and said piston, biasing means acting between said piston and said cylinder member in a direction to compress a combustible charge therebetween and to oppose movement thereof in response to combustion of a charge, said biasing means being of sufficient strength to absorb and return substantially all energy imparted thereto resulting from combustion of a charge in said engine providing an effective power delivery during the compression stroke of the engine, means connected to said cylinder member for movement therewith providing a first output drive connection from said engine, and means connected to said piston for movement therewith providing an output drive connection separate from said first output connection.

2. An internal combustion engine of the character described, comprising a mounting framework, a cylinder member and a piston movable in said cylinder member defining therewith a power cylinder including a combustion chamber, means mounting said cylinder member and said piston in sliding relation on said frame for relative movement with respect to each other in a direction paral lel to the axis of said cylinder member, means connected to supply combustible charges to said power cylinder in timed relation to relative movement of said piston and said cylinder member for combustion in said power cylinder to produce opposite movements of said cylinder member and said piston, biasing means acting between said piston and said cylinder member in a direction to compress a combustible charge therebetween and to oppose movement thereof in response to combustion of a charge, said biasing means being of sufficient strength to absorb and return substantially all energy imparted thereto resulting from combustion of a charge in said engine providing an effective power delivery during the compression stroke of the engine, means connected to said cylinder member for movement therewith providing a first output drive connection, and means connected to said piston for movement therewith providing an output drive connection separate from said first output connection.

3. A self-powered cutting machine of the character described, comprising a mounting framework, a pair of cutting blades, means mounting said blades on said framework for cooperative relative movement along their respective lengths to produce a cutting action, an internal combustion engine having a cylinder member and a piston movable in said cylinder member, means mounting said cylinder member on said frame for free movement with respect to said framework in a direction parallel to the direction of movement between said piston and said cylinder member, biasing means acting between said piston and said cylinder member in a direction to compress a combustible charge therebetween, said biasing means being of sufficient strength to absorb and return substantially all energy imparted thereto resulting from combustion of a charge in said engine providing an effective power delivery during the compression stroke of the engine, means providing a direct drive connection between said cylinder member and one of said blades, and means providing a direct drive connection between said piston and the other of said blades.

4. A self-powered cutting machine, comprising a mounting framework, a pair of elongated toothed cutting blades, means mounting said blades on said framework in side by side relation and providing for relative lengthwise movement thereof to produce a cooperative cutting action between the teeth of said blades, an internal combustion engine having a cylinder member and a piston movable in said cylinder member, biasing means acting between said piston and said cylinder member in a direction to compress a combustible charge therebetween, said biasing means being of sufiicient strength to absorb and return substantially all energy imparted thereto resulting from combustion of a charge in said engine, means mounting said engine on said framework providing for free movement thereof in a direction parallel to the axis of said cylinder member, means connecting one of said blades to said cylinder member for movement with said cylinder member, means connecting the other of said blades to said piston for movement with said piston, and clutch means in one of said connecting means providing for disconnection of the drive to one of said blades.

5. A self-powered cutting machine, comprising a mounting framework, a pair of elongated toothed cutting blades, means mounting said blades on said framework in side by side relation and providing for relative lengthwise movement thereof to produce a cooperative cutting action between the teeth of said blades, an internal combustion engine having a cylinder member and a piston movable in said cylinder member, biasing means acting between said piston and said cylinder member in a direction to compress a combustible charge therebetween, said biasing means being of sufficient strength to absorb and return substantially all energy imparted thereto resulting from combustion of a charge in said engine, means mounting said engine on said framework providing for free movement thereof in a direction parallel to the axis of said cylinder member, means connecting one of said blades directly to said cylinder member for movement therewith, means connecting the other of said blades directly to said piston for movement therewith, and bufier means on said frame engageable with said engine defining the limits of relative movement between said engine and frame.

6. The method of obtaining power from an internal combustion engine having a cylinder member and a piston member defining a power cylinder including a combustion chamber, comprising the steps of mounting both the piston and cylinder members for essentially free movement in space along the axis of the cylinder member to vary the volume of the power cylinder, biasing said members in relative directions to reduce the volume of thepower cylinder and produce a compression stroke, supplying combustible charges into the power cylinder in timed relation to compression stroke movement, igniting the compressed charges to cause combustion in the power cylinder and thus to produce force expanding the volume of the power cylinder against the bias while preventing said members from striking a blow upon each other during normal running of the engine by the biasing means, and connecting each of said members separately to a load for powered reciprocating movement of the load corresponding to each member in opposition to the other load.

7. The method of obtaining power from an internal combustion engine having a cylinder member and a piston member defining a power cylinder including a combustion chamber, comprising the steps of mounting both the piston and cylinder members for essentially free movement in space along the axis of the cylinder member to vary the volume of the power cylinder, biasing said members in relative directions to reduce the volume of the power cylinder and produce a compression stroke, supplying combustible charges into the power cylinder in timed relation to compression stroke movement, igniting the compressed charges to cause combustion in the power cylinder and thus to produce force expanding the volume of the power cylinder against the bias while preventing said members from striking a blow upon each other during normal running of the engine by the biasing means, connecting a first load for powered reciprocating movement with said cylinder member, and connecting a second load for powered reciprocating movement with said piston member in opposition to said first load.

References Cited in the file of this patent UNITED STATES PATENTS 12 8,4516 Beach July 2, 1872 1,769,254 Campbell July 1, 1930 1,770,091 Soss July 8, 1930 2,162,416 Boddinghouse June- 13, 1939 2,575,038 Banka Nov. 13, 1951 2,628,599 Wilson et al Feb. 17, 1953 

